Field of the Invention
An embodiment of this invention relates to control apparatus for a gas-turbine aeroengine.
Description of the Related Art
A gas-turbine aeroengine is typically equipped with at least a high-pressure turbine rotated by injection of high-pressure gas produced upon ignition/combustion of an air-fuel mixture in a combustion chamber and with a low-pressure turbine located downstream of the high-pressure turbine to be rotated by low-pressure gas exiting the high-pressure turbine. In such a gas-turbine aeroengine, a fuel supply command value Wf is ordinarily calculated based on a desired low-pressure turbine rotational speed N1 calculated in response to a thrust lever operation angle and control is performed to achieve this value. Fluctuation of the compressor outlet pressure P3 therefore causes fluctuation of the fuel quantity Wf.
Aside from the above, air flowing through a high-pressure compressor connected to the high-pressure turbine is bled from a compression passage to a duct (bypass) side through a BOV (Bleed Off Valve). When the BOV is closed, the amount of bleed air decreases as the BOV opening decreases, so that a compressor outlet pressure P3 transiently rises owing to an increase in the amount of air flowing on the compression passage side.
As this increases the fuel quantity Wf, the low-pressure turbine rotational speed rises to produce stronger engine thrust, which may give the crew an unnatural feeling. This becomes significant when the fuel supply command value is calculated as a ratio Wf/P3 of the fuel quantity Wf relative to the compressor outlet pressure P3.
PCT Japanese Publication No. 2008-530443 (Patent Document 1) teaches a technique for controlling fuel supply in a gas turbine engine which suppresses engine thrust fluctuation by regulating opening of a fuel supply valve (over-thrust countermeasure valve)